Personal tracking devices have been found to be useful in locating lost objects and, more importantly, missing persons. Such tracking devices typically use a network of Global Positioning Satellites (GPS) in low earth orbit that broadcast precise timing signals from on-board atomic clocks. Using triangulation formulas, a device that picks up signals from several satellites simultaneously can determine its position in global coordinates, namely latitude and longitude. Thus, an object and/or person carrying the GPS device may be located provided the appropriate equipment and trained personnel are available for determining the location of the GPS device. However, GPS signals, like any other satellite signal, are prone to numerous interferences including atmospheric disturbances, such as solar flares and naturally occurring geomagnetic storms. In addition, man-made interference can also disrupt, or jam, GPS signals. Further, anything that can block sunlight can block GPS signals. This raises the question of whether or not GPS is reliable in locating a missing and wandering person who may be in, or next to, a building, under a tree, in the brush, under a bridge, in an urban environment, in a vehicle or even a person who has fallen down and has their GPS unit covered by their own body.
Other known tracking devices use radio signal emitting transmitters. However, these types of tracking devices require an expensive receiver device in the area to receive and track the emitted radio signal. Thus, without the appropriate receiving device in the area and/or trained personnel capable of operating the receivers, these tracking devices would be useless for locating lost objects and/or missing persons.
Overview of Emergency Call Location
In a series of orders (including FCC Orders 96-264, 99-96, and 99-245), under docket 94-102, the United States Federal Communications Commission (FCC) mandated that wireless (Cellular, Personal Communications Systems (PCS), Specialized Mobile Radio (SMR)) carriers support emergency services calling for wireless phone users. The FCC's Enhanced 9-1-1 Phase II, emergency services for wireless users with automatic high accuracy location, was scheduled for implementation in October 2001.
The European Union and member nations followed suit in implementing a universal short-code emergency services number (1-1-2) with “best-effort” location in 2003 and the telematics-focused “eCall” initiative. eCall is expected to be implemented co-incident with the operational status of the “Galileo” Global Navigation Satellite System (GNSS). Galileo is to be similar in function to the United States NavStar Global Positioning System (GPS).
Standardization of Emergency Call Location
To allow for delivery of caller location to the emergency responders (in the United States, a public safety answering point (PSAP) commonly handles dispatching Fire, Police, or Ambulance first responders based on 9-1-1 emergency calls) across multi-vendor networks, standardization efforts were undertaken prior to deployment. A joint European Telecommunications Standards Institute (ETSI) and American National Standards Institute (ANSI) project, facilitated by the Telecommunications Industry Alliance (TIA) and industry representatives, was conceived to handle standardization for the North American market.
The methods and means for position reporting to emergency services systems, as mandated by the FCC in the E911 Phase II mandate, was addressed for North American wireless carriers in Joint ETSI/ANSI Standard 36 (J-STD-036). The J-STD-036 standard provides basic definitions, formats and constraints, and defines the messaging required to transfer identity information, call control information and location-reporting about wireless emergency services callers between wireless and wired network servers enabling coordination between public safety agencies, wireless carriers, equipment manufacturers, and local wireline carriers.
A wireless location system determines geographic position and, in some cases, the speed and direction of travel of wireless devices. Wireless location systems use uplink (device-to-network) signals, downlink (network-to-device) signals, or non-communications network signals (fixed beacons, terrestrial broadcasts, and/or satellite broadcasts). Network-based location solutions use specialized receivers and/or passive monitors within, or overlaid on, the wireless communications network to collect signaling used to determine location. Network-based techniques include uplink Time-Difference-of-Arrival (TDOA), Angle-Of-Arrival (AOA), Multipath Analysis (RF fingerprinting), and signal strength measurement (SSM).
Mobile-based location solutions use the mobile receivers or ancillary receivers in the mobile device to collect signaling from the wireless network, satellite broadcasts or terrestrial broadcasts. Mobile-based techniques may use assistance data (for instance broadcast information) but calculate the position estimate locally. Mobile-based location solutions may be WCN independent (where WCN refers to the wireless communications network).
Mobile-assisted location solutions employ the mobile receiver or ancillary receivers in the mobile device to collect signaling from the wireless network, satellite broadcasts or terrestrial broadcasts. Mobile-assisted location takes advantage of assistance data delivered over the wireless network and delivers collected signal data to a landside server for final position estimation.
Mobile-based or Mobile-assisted (e.g. Device-based) location techniques include CID (serving Cell-ID), CID-RTF (serving cell-ID plus radio time-of-flight time-based ranging), CIDTA (serving cell-ID plus time-based ranging), Enhanced Cell-ID (ECID, a serving cell, time-based ranging and power difference of arrival hybrid), Advanced-Forward-Link-Trilateration (AFLT), Enhanced Observed Time Difference (E-OTD), Observed-Time-Difference-of-Arrival (OTDOA) and Global Navigation Satellite System (GNSS) positioning. An example of a GNSS system is the United States NavStar Global Positioning System (GPS).
Hybrids of the network-based and mobile device-based techniques can be used to generate improved quality of services including improved speed, accuracy, yield, and uniformity of location. Hybrids also provide a fall-back location capability in case of location failure.
Subscriber Identity Module (SIM)
A dual SIM mobile phone is one which holds two SIM cards in order for the subscriber to maintain two subscriptions with two different network operators with one mobile device. Originally, dual SIM phones switched between the active and standby SIMS and between WCNs allowing a split between paging and origination to optimize coverage and cost. Such standby dual SIM phones typically had a single wireless transceiver module. Newer, active dual SIM phones hold two SIM cards and two wireless transceiver modules and allow for concurrent registration and operation in two wireless communications networks. The term “SIM” is used herein in place of the Global System for Mobility (GSM) Subscriber Identity Module (SIM), the 3rd Generation Partnership Program (3GPP) Universal Subscriber identity module (U-SIM), The 3rd Generation Partnership Program 2 (3GPP2) CDMA Subscriber Identify Module (CSIM) or Removable User Identity Module (R-UIM) and the 3GPP's 4G Subscriber Identity Module (4GSIM).
The air interface protocols now used in the wireless industry include AMPS, N-AMPS, TDMA, CDMA, TS-CDMA, OFDM, OFDMA, GSM, TACS, ESMR, GPRS, EDGE, UMTS, WCDMA, WiMAX, LTE and others. The term CDMA will be used to refer to the CDMA digital cellular (TIA/EIA TR-45.4 defined IS-95, IS-95A, IS-95B), Personal Communications Services (J-STD-008), and 3GPP2 defined CDMA-2000 and UMB standards and air interfaces. The term UMTS will be used to refer to the 3GPP specified Wideband-CDMA (W-CDMA) based Universal Mobile Telecommunications System, defining standards, and radio air interface. The term WiMAX is used to denote the IEEE defined 802.16, “Broadband Wireless”; 802.20, “Mobile Broadband Wireless Access”; and 802.22, “Wireless Regional Area Networks” technologies. The present invention also applies to the 3GPP defined Long-Term-Evolution (LTE) and the 3GPP LTE-Advanced system among others.